Gausemycins A,B: Cyclic Lipoglycopeptides fromStreptomycessp.**

Abstract

AbstractWe report a novel family of natural lipoglycopeptides produced byStreptomycessp. INA‐Ac‐5812. Two major components of the mixture, named gausemycins A and B, were isolated, and their structures were elucidated. The compounds are cyclic peptides with a unique peptide core and several remarkable structural features, including unusual positions ofd‐amino acids, lack of the Ca2+‐binding Asp‐X‐Asp‐Gly (DXDG) motif, tyrosine glycosylation with arabinose, presence of 2‐amino‐4‐hydroxy‐4‐phenylbutyric acid (Ahpb) and chlorinated kynurenine (ClKyn), and N‐acylation of the ornithine side chain. Gausemycins have pronounced activity against Gram‐positive bacteria. Mechanistic studies highlight significant differences compared to known glyco‐ and lipopeptides. Gausemycins exhibit only slight Ca2+‐dependence of activity and induce no pore formation at low concentrations. Moreover, there is no detectable accumulation of cell wall biosynthesis precursors under treatment with gausemycins.